Damage identification of RDT non-metal motor sheath based on helical guided wave

Abstract

In order to obtain the healthy state of the motor sheath of the Rim-Driven Thruster (RDT) in service, a method for identifying damage to the non-metal sheath of the RDT motor based on helical guided waves is proposed. Damage detection is performed on a non-metal hollow cylinder (110 mm of outer diameter and 3.2 mm of wall thickness). A pair of MFC sensors are arranged on the surface of the cylinder to excite and receive the helical guided waves, and the non-metal sheath of the RDT motor damage monitoring model is established. The space expansion method is used to complete the tracking of the helical guided wave packet and determine the propagation order of the helical guided wave. U sing the short-time wavelet entropy (STWE) algorithm to complete the calculation of the energy entropy of the damage signal, and compare the energy entropy in the non-destructive state to finish the damage identification. The experimental results show that by arranging the sensor in a certain area outside the cylindrical structure to be detected to excite the spiral guided wave, the damage identification of the difficult-to-detect area and the small damage can be realized.